JPH0747587A - T-die - Google Patents

Abstract

PURPOSE:To provide a T-die in which a film and a sheet completely without the generation of edge warping or unevenness can be molded and the adhesion of leaked resin to the film is prevented and also the changing of film width can be carried out easily even in the case of using polypropylene, ethylene-vinyl acetate or the like. CONSTITUTION:In a T-type extrusion die 1 comprising a manifold section 2, a land section 3, a lip section 4, an inner deckle for controlling the width of molten resin flow and an inner deckle bar for controlling the film width, heat pipes are disposed in parallel each other in the longitudinal direction of the T-die 1 on both sides of the manofold section 2, and at last parts of the outer faces of two heat pipes are exposed in the monifold section 2 all over the whole length of the manifold section 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a T-shaped extrusion die (T) for molding a film or sheet made of a synthetic resin such as polyethylene, polypropylene or ethylene vinyl acetate.
Regarding dies), more specifically, the conventional film such as polypropylene or ethylene vinyl acetate has a high height (edge beads generated at both ends of the film) and uneven thickness (uneven thickness).
The present invention relates to a T-die which is particularly suitable for forming a film or a sheet using a synthetic resin in which the above-mentioned phenomenon has occurred.

[0002]

2. Description of the Related Art As a method for molding a polyethylene or polypropylene film, there are an inflation method and a T-die method. Of these, the T-die method is used to extrude a film such as polyethylene and stack it on a metal foil, cellophane paper, kraft paper, etc. while it is hot and roll it to form a fertilizer bag, moisture-proof bag, etc. Further, it is widely used for manufacturing packaging materials such as medicine packaging materials and food packaging materials, and various resin sheets.

Various attempts have been proposed to improve such a T-die to efficiently produce a suitable film. For example,
Registered utility model by the inventor of the present invention No. 1726281
No., utility model registration No. 1603083, utility model registration No. 1777587, patent No. 1568629, patent No. 1
631933 and the like. According to the conventional T-die according to these proposals, a film having excellent transparency is generally obtained, and when a specific resin such as polyethylene is used, the thickness is uniform and the ear height is not generated, and a product which is almost satisfactory is obtained. Was obtained.

[0004]

However, the synthetic resins used in the T-die method have become extremely diverse, and in addition to high / medium / low density polyethylene (PE), polypropylene (PP), ethylene vinyl acetate, etc. Various types of resins such as (EVA), ionomer, LLDP, EVOH, and EAA have come to be used. Further, the characteristics of the resin obtained by the method of producing the resin such as the autoclave method and the tubular method are different, and in this respect also, the characteristics of the synthetic resin used in the T die method are various.

Therefore, the conventional T-die still has a problem that the height of the ears is generated at both ends of the film and the thickness is apt to become uneven depending on the kind of resin used, and particularly polypropylene and ethylene vinyl acetate are used. The problem when used was remarkable.

FIGS. 5 to 7 show an example of a conventional T-die described in Japanese Patent No. 1631933. 5 is a front view of the conventional T die described above, FIG. 6 is an enlarged front cross-sectional view of a side plate of the T die of FIG. 5, and FIG. 7 is a cross-sectional view of the Y-Y cross section of the T die of FIG.

5 to 7, the T die 1'includes a manifold portion 2 ', a land portion 3', a lip portion 4 ', an inner deckle 5'and an inner deckle rod 6'. The inner deckle 5'is supported by the support rod 12 ', and is located from the upper end of the manifold portion 2'to the lower end of the land portion 3'. The inner deckle rod 6'is located at the lowermost end of the land portion 3 ', and is arranged with a predetermined gap with the inner deckle 5'.
The inner deckle 5'is divided into an embedded inner deckle portion (upper inner deckle portion) 5a 'and a flagged inner deckle portion (lower inner deckle portion) 5b'.

In FIG. 5, arrows indicate the flow of resin,
The molten resin extruded from the extruder A ′ flows into the land portion 3 ′ through the manifold portion 2 ′, the width of the resin flow is regulated by the inner deckle 5 ′, and finally the inner deckle rod 6 ′ strictly regulates the resin. Is determined and the thickness of the resin is controlled by the lip portion 4'to obtain a film.

In such a conventional T-die, the temperature of the T-die is usually set to the temperature of the molten resin (T-die inlet temperature by an external heater (not shown) disposed outside the T-die at intervals of about 180 mm. However, the resin temperature was not always uniform due to the distance from the external heater and the heat generation of the resin. Further, the resin flow in the conventional T-die tends to be faster toward the center of the T-die, as indicated by the arrow in FIG. Therefore, in the conventional T-die, depending on the type of resin used, the unevenness of the resin temperature and the uneven flow of the resin described above are combined to cause ear height and uneven thickness, and especially polypropylene and ethylene vinyl acetate are used. When used, ear height and uneven thickness certainly occurred.

Further, in the conventional T-die, the resin accumulated in the portion between the inner deckle 5'and the side plate 16 '(the hatched portion in FIG. 6) forms the inner deckle rod 6'and the lip portion 4'. There was also a problem that it leaked from the gap and adhered to the film. The frequency of occurrence of this resin leakage is particularly high when a narrow film is manufactured, and
It may occur at a high frequency of once or more every 5 minutes, resulting in deterioration of product quality and yield. Further, since the leaked resin becomes an oxidized resin and adheres to the periphery of the lip portion 4 ', the movement of the inner deckle rod 6'is hindered, and it is necessary to remove the oxidized resin when changing the width of the film.

The present invention has been made in view of the above problems of the prior art, and it has been completed in the past even when a synthetic resin such as polypropylene or ethylene vinyl acetate in which the height of the ears and uneven thickness is generated is used. It is an object of the present invention to provide a T-die that can form a film or sheet having no peak height or uneven thickness, prevent leakage resin from adhering to the film, and facilitate the width changing operation of the film.

[0012]

As a result of intensive studies to achieve the above-mentioned object, the present inventor has arranged heat pipes on both sides of a manifold portion and has the outer surface of the heat pipe over the entire length of the manifold portion. The inventors have found that the above problems can be solved by exposing the inside of the manifold portion by means of the above, and have reached the present invention.

That is, the present invention is a T-shaped extrusion die for extrusion-molding a synthetic resin film,
(1) A manifold section for distributing the molten synthetic resin introduced into the T-die in the longitudinal direction of the T-die, and (2) a narrow groove for allowing the molten resin to pass from the manifold section to the resin extrusion port. -Shaped land portion (land), (3) a lip portion for controlling the thickness of the film obtained by adjusting the width of the resin extrusion port, (4) in both ends of the manifold portion and the land portion. And an inner deckle that is movable parallel to the longitudinal direction of the T-die and that regulates the width of the flow of molten resin, and (5) that is placed in both ends near the resin extrusion port of the land part. And is movable in parallel with the inner deckle,
In a T-die having an inner deckle rod for controlling the width of the obtained film, heat pipes are arranged parallel to the longitudinal direction of the T-die on both sides of the manifold part, and the outer surface of the heat pipe is further provided. At least a part of which is exposed in the manifold portion over the entire length of the manifold portion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The T-die of the present invention will be described below more specifically with reference to the drawings.

FIG. 1 is a front view showing an embodiment of the T-die of the present invention, FIG. 2 is an enlarged front sectional view in the vicinity of a side plate of the T-die of FIG. 1, and FIG. 3 is an X-X of the T-die of FIG. FIG. 4 is a cross-sectional view showing another embodiment of the T-die of the present invention.

First, the functions of the main components of the T-die of the present invention will be described below with reference to FIGS.

(1) Manifold part 2 The manifold part 2 is a passage having a circular, elliptical, teardrop-shaped cross section, and extends in the longitudinal direction at the center of the T-die 1. The molten resin extruded from the extruder A under high pressure spreads through the manifold portion 2 in the longitudinal direction of the T die 1 and is guided to the land portion 3.

(2) Land portion 3 The land portion 3 is a narrow groove-shaped passage, and the molten resin is guided from the manifold portion 2 to the lip portion 4 through the narrow groove-shaped land portion 3.

(3) Lip portion 4 The lip portion 4 has a narrow groove-shaped discharge orifice (resin extrusion port) 8 formed therebetween, from which molten resin under high pressure is extruded to form a film. It is possible to control the thickness of the film obtained by adjusting the interval between the lip portions 4, that is, the width of the resin extrusion port 8. Figure 3
The T die 1 described in 4 to 4 is provided with a notch 9 on one side surface below the T die 1, and a portion 10 ahead of the notch 9 is moved by a lip adjusting means 11 such as a screw so that the width of the resin extrusion port 8 is reduced. It is a so-called lip bending type T-die for adjusting. However, the adjusting method of the lip portion 4 according to the present invention is not particularly limited, and as shown in FIG.
A conventional type in which the width of the resin extrusion port 8'is adjusted by moving the lip members 10 'arranged on both sides of the T-die by a lip adjusting means (not shown) may be used.

(4) Inner deckle 5 [embedded inner deckle portion (upper inner deckle portion) 5a and flagged inner deckle portion (lower inner deckle portion) 5b are collectively referred to as "inner deckle 5"] Are arranged in both ends of the manifold part 2 and the land part 3, and the gap between the inner deckle 5 and the inner surfaces of the manifold part 2 and the land part 3 is preferably about 0.05 to 0.2 mm. Designed. Both inner deckles 5 can be moved in parallel to the longitudinal direction of the T-die 1 by the support rods 12 connected to each, and the manifold portion 2 and the land portion 3 can be adjusted by adjusting the distance between the inner deckles 5. The width of the molten resin flowing through is adjusted.

The inner deckle 5 is disclosed in Japanese Patent No. 15686.
As described in No. 29, the embedded inner deckle portion 5a
And the inner deckle part 5b with flag are divided into upper and lower parts,
Further, it is desirable that support rods 12a and 12b are connected to each. With this configuration, the embedded inner deckle portion 5a and the flagged inner deckle portion 5b can be individually adjusted, and the resin width can be regulated more smoothly.

(5) Inner deckle rod 6 The inner deckle rod 6 is provided between the resin extrusion port 8 and the lower end of the inner deckle 5 in both ends of the land portion 3.
The inner deckle 5 is arranged with a predetermined gap from the lower end, preferably with a gap of about 0.1 to 0.5 mm. The inner deckle rods 6 are respectively associated with the inner deckle 5 and movable in parallel, and the width of the molten resin flowing through the land portion 3 is finally adjusted by adjusting the distance between the inner deckle rods 6, The width of the resulting film is controlled.

Next, the characteristic portion of the T-die of the present invention will be described with reference to the drawings.

In the T-die 1 of the present invention, as shown in FIGS. 1 to 4, heat pipes 7 are arranged on both sides of the manifold portion 2 in parallel with the longitudinal direction of the T-die 1. At least a part of the outer side surface is exposed in the manifold portion 2 over the entire length of the manifold portion 2.

Heat pipe 7 used in the present invention
Is a heat-conducting pipe that contains a suitable heat medium inside. Even if it is partially heated, the heat quickly spreads over its entire length, and the temperature of the whole is always kept uniform. It is what is done. The heat pipe 7 shown in FIGS. 1 to 4 is a hermetic type that does not have a heating means dedicated thereto, and the temperature of the T die 1 heated by an external heater (not shown) and the temperature of the molten resin that comes into contact with it. Heated by and
The temperature of the entire heat pipe 7 is maintained at an average temperature of those temperatures. The heat pipe according to the present invention is not particularly limited to the above, and may be a type having an appropriate heating means dedicated to the heat pipe.

The heat medium used in the heat pipe is preferably one having various characteristics such as high thermal stability and thermal conductivity, low corrosiveness, and no flammability / ignitability, such as naphthalene and naphthalene. The temperature of the melted resin (usually 18
0 to 340 ° C).

The material of the heat pipe is preferably a material that is not corroded by the heat medium, has pressure resistance and high thermal conductivity, and examples thereof include stainless steel and brass. Further, the surface of the heat pipe is preferably plated with hard chrome or the like in order to prevent oxidation and adhesion of the molten resin which comes into contact with the surface and to enhance the slidability of the surface.

If the outer surface of the heat pipe 7 constitutes a part of the inner surface of the manifold portion 2 as described above,
Since the molten resin flowing from the manifold portion 2 into the land portion 3 is in direct contact with the heat pipe 7 having a uniform temperature, the non-uniform resin temperature due to heat generation or the like is completely equalized in the vicinity of the heat pipe 7. Further, if the resin temperature becomes uniform, the non-uniformity of the resin flow can be corrected. Therefore, according to the T-die 1 of the present invention, it is possible to prevent the occurrence of ear height and uneven thickness, and it is possible to obtain a film having no ear height and uneven thickness even when polypropylene or ethylene vinyl acetate is used.

Further, in the T die 1 of the present invention, as shown in FIG.
It is preferable that at least a part of the outer surface of the heat pipe 7 projects into the manifold portion 2 as shown in FIGS. The outer surface of the heat pipe 7 is preferably 3 to 4 m
By projecting about m in the manifold part 2,
The pressure of the molten resin flowing from the manifold portion 2 into the land portion 3 is uniformly controlled by the action of the nozzle formed between the two heat pipes 7. Therefore, according to the T-die 1 of the present invention configured as described above, the resin flow is made more uniform, so that there is a tendency that the occurrence of ear height and uneven thickness is more reliably prevented.

When the heat pipe 7 projects into the manifold portion 2 as described above, it is necessary to form a groove in the inner deckle 5 corresponding to the outer surface of the heat pipe 7. This groove is preferably designed so that the gap between the inner deckle 5 and the heat pipe 7 is about 0.2 to 0.5 mm in order to prevent damage to the heat pipe 7 due to the inner deckle 5.

Further, in the T die 1 of the present invention, as shown in FIG. 4, heat pipes 13 are arranged on both sides of the land portion 3 in parallel with the longitudinal direction of the T die 1, and the outer surface of the heat pipe 13 is disposed. It is preferable that at least a part of the above is exposed in the land portion 3 over the entire length of the land portion 3. According to this structure, the molten resin flowing down the land portion 3 is completely homogenized again near the heat pipe 13,
It is likely that the height of the ears and uneven thickness will be more reliably prevented without being affected by the resin heat generation or the like in the land portion 3.

The width of the land portion of the conventional T die is usually 4 to 5 mm, while the width of the land portion 3 of the T die 1 of the present invention is preferably 2.7 to 3.2 mm. If the land portion 3 is narrowed in this way, the pressure of the molten resin is controlled more uniformly by the action of the nozzle formed between the land portions 3, and the molten resin contacts the heat pipe 7 more uniformly, The resin flow and resin temperature tend to be more uniform. Therefore, narrowing the width of the land portion 3 in the T-die 1 of the present invention is particularly effective in more surely preventing the occurrence of ear height and uneven thickness. If the width of the land portion 3 is too narrow, the strength of the inner deckle 5 and the inner deckle rod 6 becomes insufficient, which is not preferable.

In the T-die 1 of the present invention, further, the inner deckle 5, especially the embedded inner deckle portion 5a.
It is preferable to make the shape of the following special shape which is not existent in the prior art. That is, the conventional inner deckle 5 ',
In particular, the embedded inner deckle portion 5a 'had a resin flow control surface 14' perpendicular to the longitudinal direction of the T-die, as shown in FIGS. On the other hand, in the T-die 1 of the present invention, as shown in FIGS. 1 to 4, the resin flow control surface 14 of the embedded inner deckle portion 5a is inclined outward with respect to the vertically downward direction over the entire surface. Preferably. By eliminating the resin flow control surface perpendicular to the longitudinal direction of the T-die in this way, the flow of the molten resin flowing from the manifold portion 2 to the land portion 3 becomes smooth,
Further, since the resin pressure is made more uniform, the height of the ears and the occurrence of uneven thickness tend to be more reliably prevented.

In the inner deckle 5 of the T-die 1 of the present invention, a part of the molten resin is formed behind the inner deckle 5, that is, the inner deckle 5 and the side plate 16 as shown by an arrow in FIG. It is preferable that a notch 15 is formed so as to wrap around the portion between them (see FIGS. 2 to 4). If you have this notch 15,
The resin pressure in the shaded area in FIG. 2 increases, and the inner deckle rod 6 is pressed against the upper end surface of the lip portion 4 by the pressure, so that the inner deckle rod 6 and the lip portion 4
Resin leakage between and is completely prevented. for that reason,
Leakage resin does not adhere to the film, improving product quality and yield. Further, since the oxidized resin does not adhere to the periphery of the lip portion 4, the movement of the inner deckle rod 6 is always smooth, and the film width changing operation is facilitated.

The size of the cutout (thickness of the cutout portion) is preferably about 1.5 to 5.0 mm, particularly preferably about 3 mm so that sufficient pressure is applied to the shaded portion in FIG.

In the T-die of the present invention, the side plate 16 is provided with a purging plug 17 for removing the resin between the inner deckle 5 and the side plate 16 when the space between the inner deckle 5 is widened. It is preferable (see FIG. 2).

In the T die of the present invention, in order to efficiently heat or cool the inside of the T die 1 when changing the type of resin, a heat insulating cover (not shown) surrounding the upper portion of the T die 1 and a cooling means ( (Not shown) or the like may be provided.

[0038]

As described above, in the T die of the present invention, since the resin temperature and the resin flow are made uniform,
By using the T-die of the present invention, the occurrence of ear height and uneven thickness can be completely prevented regardless of the type of resin used. Therefore, according to the T-die of the present invention, a synthetic resin such as polypropylene or ethylene vinyl acetate, which has a very low yield due to ear height and uneven thickness, has been used so far. It becomes possible to form films and sheets.

Further, in the T-die of the present invention, it is possible to completely prevent the resin leakage from the space between the inner deckle rod and the lip portion and to completely prevent the leakage resin from adhering to the film. Product quality and yield are significantly improved. Further, since the oxidized resin does not adhere to the periphery of the lip portion, the inner deckle rod can be moved smoothly at any time, and the film width changing operation is facilitated.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a T-die of the present invention,

2 is an enlarged front cross-sectional view of the vicinity of the side plate of the T die of FIG. 1,

3 is a cross-sectional view of the T-die of FIG. 1 taken along the line XX,

FIG. 4 is a sectional view showing another embodiment of the T-die of the present invention,

FIG. 5 is a front view showing an example of a conventional T die,

6 is an enlarged front cross-sectional view of the vicinity of the side plate of the T die of FIG. 5,

7 is a cross-sectional view taken along line YY of the T-die of FIG.

[Explanation of symbols]

1: T-die, 2: Manifold part, 3: Land part, 4:
Lip portion, 5: inner deckle, 5a: embedded inner deckle portion (upper inner deckle portion), 5b: flagged inner deckle portion (lower inner deckle portion),
6: Inner deckle rod, 7: Heat pipe, 8: Resin extrusion port, 9: Notch on the side of the T die, 10: Moving part of the tip of the T die, 11: Lip adjusting means, 12, 12a, 1
2b: support rod, 13: heat pipe, 14: inner deckle resin flow control surface, 15: notch of inner deckle, 16: side plate, 17: purging plug, A: extruder.

Claims (6)

[Claims] 1. A T-shaped extrusion die for extrusion-molding a synthetic resin film, comprising: (1) a method for distributing a synthetic resin in a molten state introduced into a T-die in a longitudinal direction of the T-die. Manifold part, (2) narrow groove-shaped land part for passing molten resin from the manifold part to the resin extrusion port, and (3) controlling the thickness of the film obtained by adjusting the width of the resin extrusion port Lip part for
(4) An inner deckle that is arranged in both ends of the manifold portion and the land portion, is movable in parallel to the longitudinal direction of the T-die, and regulates the width of the flow of the molten resin; ) Inner deckle rods arranged in both ends of the land portion in the vicinity of the resin extrusion port, associated with the inner deckle and movable in parallel, and having an inner deckle rod for controlling the width of the obtained film. In the T-die, heat pipes are arranged on both sides of the manifold portion in parallel to the longitudinal direction of the T-die, and at least a part of the outer surface of the heat pipe is inside the manifold portion over the entire length of the manifold portion. A T-die that is exposed. 2. The heat pipe according to claim 1, wherein at least a part of an outer surface of the heat pipe projects into the manifold portion, and a groove corresponding to the outer surface of the heat pipe is formed on the inner deckle. T-die. 3. Heat pipes are also arranged on both sides of the land portion in parallel to the longitudinal direction of the T-die, and at least a part of the outer surface of the heat pipe is within the land portion and over the entire length of the land portion. The T-die according to claim 1, which is exposed. 4. The inner deckle is divided into upper and lower portions of an embedded inner deckle portion and a flagged inner deckle portion, and a resin flow control surface of the embedded inner deckle portion is entirely outside in a vertically downward direction. The T-die according to any one of claims 1 to 3, which is inclined to. 5. The T according to claim 1, wherein the inner deckle is formed with a notch for allowing a part of the molten resin to wrap around behind the inner deckle. Die. 6. The width of the narrow groove-shaped land portion is 2.7 to
The T-die according to any one of claims 1 to 5, which is 3.2 mm.